import java.util.Random;
import java.util.TreeSet;

public class 验证码 {
    public static void main(String[] args) {
        Random rand = new Random();
        int n = rand.nextInt(10);
        int pos=rand.nextInt(5)+1;
        String x="";
        for (int i = 0; i < 5; i++) {
            if(i==pos){
                x=x+n;
            }
            else{
                boolean t=rand.nextBoolean();
                if(t){ x += (char) (rand.nextInt(26) + 'A');}
                else{ x += (char) (rand.nextInt(26) + 'a');}

            }
        }
        System.out.println(x);

    }
}
